The invention is directed generally to pump structures of the reservoir type, and more particularly to a novel reservoir construction in which a filled reservoir may be readily interchanged with an empty reservoir at the pump site.
Reservoir type pumps are extensively employed, particularly in connection with the lubrication of machinery and the like whereby such machinery may be periodically supplied with lubricant from the reservoir with the lubricant pump discharging lubricant at any suitable number of locations at which lubrication is required. By use of the reservoir a reasonable supply of lubricant may be provided at the pump with the reservoir being refilled periodically. As the invention has particular application to lubrication systems, it will be described in this context.
In lubricant reservoirs of the type referred to, the lubricant is supplied to the pump proper under pressure, as distinguished from a gravity feed, with the pressure normally being provided by an external separate pumping means, through which a coiled compression spring and piston within the reservoir is compressed in the filling. Heretofore, reservoirs of this type were a unitary part of the pump structure and provided with a suitable fill connection through which lubricant could be forced. It has been customary in connection with such filling operations to employ a relatively large supply of lubricant in a container, transport the container to the location of the pump, operatively connect the supply container with the reservoir by means of a suitable conduit and then suitably pump the lubricant into the reservoir in opposition to the pressure exerted by the piston and spring.
The use of a piston and spring in a reservoir, of the type here involved, to preload the contents supplied, prevents the possibility of readily filling the reservoir by removing a cover and discharging the material directly into the reservoir. As a matter of fact, extreme care must be taken with respect to reservoirs of this type as the spring pressures may be over 200 pounds per square inch and the opening of a reservoir of this type for filling purposes would create considerable problems with respect to the control of the spring involved. For example, if the cover of the reservoir could be removed, upon loosening the same, the spring pressure would propel the cover therefrom with possible injury to personnel. Irrespective thereof, obviously if the reservoir were filled with a liquid or viscous material it would be exceedingly difficult to place the piston in proper position and then compress the spring to enable the cover to be secured to the reservoir.
To eliminate possible injury to personnel when the reservoir is being taken apart, it is customary to provide some form of connection between the piston and the cover member of the reservoir against which the opposite end of the piston bears whereby the compression spring is always preloaded and cannot freely expand. Such restriction may be of various types, for example a rod rigidly secured to the piston and extending through an opening in the reservoir cover with the free end of the rod provided with a suitable abutment preventing separation between it and the cover. In other constructions, the connecting member between piston and cover may, for example, be of chain-like formation, thereby eliminating rod movement exteriorly of the cover. In view of this type construction, it is usually customary to provide a supply port or fitting which may be normally closed suitably and protected by a plug or cover member which is removed to accommodate reception of the supply conduit previously referred to, which for example may be threaded into or otherwise secured to such a supply port. The lubricant may then be supplied under pressure, sufficiently great to effect a compression of the coiled compression spring within the reservoir.
Supply operations of this type have two principal disadvantages, the first being that normally a series of pumps are to be filled and the supply container thus is relatively large and bulky and second the in situ refilling of the pump reservoirs presents a problem with respect to cleanliness. In the operation of large machinery and equipment requiring extensive lubrication, it is substantially essential that clean, uncontaminated lubricant be supplied as foreign matter in the lubricant might result in damage to the machinery.
Many pieces of machinery falling into the general type heretofore referred to are employed in locations which render refilling of a reservoir particularly difficult with respect to cleanliness. One typical example is in coal mines with respect to mining machinery and the like. Numerous other types of machinery involve the same general problem, for example in steel mills, etc.
The problem is a serious one and many companies have gone to great lengths in an effort to avoid improper lubrication. For example, many companies have built so-called "clean rooms" in which lubricant is filled in the supply containers from which the reservoirs are subsequently filled. However, obviously this measure solves merely a part of the problem, as it does not insure the ultimate receipt of clean lubricant into the pump reservoir, merely that the supply will be clean at the time it reaches the pump location. The problem therefore still existed of insuring that the new supply of material reaching the pump would be completely uncontaminated.